The broad, long-term objective of the proposed research is to help elucidate the neural mechanisms by which the nervous system of an animal can control and coordinate the movements which constitute behavior. Walking in cockroaches is the model system to be studied. The research will help answer three specific questions: 1) How is the neural network controlling leg movement regulated (i.e., turned on or off)? 2) How do individual controlling networks interact to achieve coordination of leg movements? 3) How does sensory feedback from a moving leg influence the subsequent movements of that and the other legs? The experimental approach will be to record the electrical activity of single neurons in the nervous system of the insect while it is walking normaly and while its nervous system is given a variety of natural or electrical stimuli. The questions posed address some of the most significant problems confronting neurobiology: how is a behavior initiated or stopped; how is coordination of different bodily parts achieved; how does an animal compensate for unexpected perturbations of its intended movements? Answers to these questions are basic to our understanding of the function of any nervous system, and such understanding is the ultimate goal of neurobiology.